In a large skillet over medium heat, add the tablespoon of olive oil and allow it to heat up.

Introduce the chopped onion to the skillet and sauté for 3-4 minutes until it softens and becomes translucent.

Add the ground beef into the skillet, breaking it apart with a spoon, and cook until the meat is browned and no longer pink, draining any excess fat if necessary.

Stir in the garlic powder, dried oregano, and black pepper, mixing well to combine the seasonings with the beef and onion.

Add the uncooked white rice into the skillet, stirring to coat it with the beef and onion mixture.

Pour in the beef broth, cream of mushroom soup, and diced tomatoes with green chilies, stirring everything together.

Bring the mixture to a boil over medium-high heat, then reduce the heat to low, cover the skillet, and let it simmer for about 20-25 minutes, until the rice is cooked through and the liquid has been absorbed.

Once the rice is ready, remove the skillet from heat and mix in the shredded cheddar cheese and sour cream, stirring until the cheese melts and the mixture is creamy.

Adjust the seasoning as needed and serve hot.